Portion of a frame for a mask



FIG. 1 is a front perspective view of a portion of a frame for a mask according to a first embodiment of our design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is a is a right side view thereof; and,

FIG. 7 is a left side view thereof.

Where included, broken lines showing environment or structure are for illustrative purposes only and form no part of the claimed design. Where included, dotted lines represent the border between claimed and not claimed subject matter and form no part of the claimed design. 

The ornamental design for a portion of a frame for a mask, as shown and described. 